Diffmate
Compare million-row CSV & Excel files in your browser — free
Diffmate launched on March 3, 2026.
What it does
Free browser tool to compare CSV, Excel, PDF & text files. No install, no signup, files never leave your device. Drop two files and see every change highlighted side by side. Handles million-row files without freezing, powered by a Web Worker diff engine. Added, modified, and deleted lines are color-coded for instant review.
Compare 68 MB CSV and million-row Excel files in your browser. Web Worker engine & virtual scrolling keep UI responsive. Free Beyond Compare alternative — zero server upload.
68 MB CSV, 1 million-row Excel — Web Worker engine & virtual scrolling keep your browser responsive. No files ever leave your device. DiffMate is a free, browser-based document comparison tool designed to help professionals find differences between two versions of any document. Whether you are comparing million-row CSV data exports, Excel spreadsheets with complex formulas, PDF contracts, or plain text configuration files, DiffMate processes everything directly in your browser — no files are ever uploaded to a server. DiffMate uses an advanced sequence matching algorithm based on Python's well-established difflib SequenceMatcher. This algorithm identifies the longest common subsequences…from diffmate.work
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csvdiff – a fast diff tool for comparing CSV files2019 · github.com · ▲21A fast diff tool for comparing csv files. Contribute to aswinkarthik/csvdiff development by creating an account on GitHub.
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